A valve such as this comprises a first duct, which admits exhaust gases into the valve, and a second duct which lets the gases out of the valve. The first duct is at right angles to the second duct and opens into a connecting portion where the second duct is connected to the first duct thereby defining an intersection that forms a seat for a valve disk that slides in the connecting portion of the second duct in a direction at right angles to the seat between a closed position in which the valve disk is pressed against the seat and a wide open position in which the valve disk is away from the seat. The valve disk is set in motion by means of an actuator moving it between its closed position and its open position in order to regulate the separation (or lift) of the valve disk with respect to its seat and thus regulate the passage cross section for the exhaust gases, the wide open position allowing a maximum flow rate of exhaust gases through the valve.
Anti-pollution standards are now making it necessary to recirculate a more substantial proportion of the exhaust gases. It has therefore been envisioned for the flow rate of exhaust gases through the valves to be increased by increasing the lift of the valve disk and/or the diameters of the valve disk and of its seat. However, solutions such as these present problems of mechanical robustness and lead to an increase in the amount of space required for the valve, this in particular being incompatible with, on the one hand, the amount of space available under the hood of vehicles which is becoming increasingly restricted and, on the other hand, the overall lightening of vehicles that vehicle manufacturers are aiming for in order to limit the fuel consumption of their vehicles.
Now, it has become apparent that turbulence in the exhaust gases appears in the vicinity of the wall of the connecting portion and disrupts the flow of the exhaust gases through the passage cross section delimited by the valve disk and its seat. These disturbances limit the maximum flow rate of exhaust gases through the valve.